Inflow control solutions for wellbores

ABSTRACT

A selectively openable inflow control sub includes a sliding sleeve valve slidable within an inner bore of the sub between a closed-port position, closing the inflow port, and an open-port position, opening the inflow port to fluid flow therethrough, the sliding sleeve valve is axially moveable from the closed-port position to the open-port position by pushing the sleeve with a mill string.

PRIORITY CLAIM

This application claims priority from U.S. Ser. No. 61/562,237, filed Nov. 21, 2011 and U.S. Ser. No. 61/613,297, filed Mar. 20, 2012.

FIELD

The invention relates to a method and an apparatus for wellbore fluid handling and, in particular, to a method and an apparatus for selective communication to a wellbore for fluid treatment and for effectively handling produced fluids.

BACKGROUND

An oil or gas well relies on inflow of petroleum products. It may be advantageous in certain circumstances to control the inflow of produced fluids. For example, it may be advantageous to screen the produced fluids before they enter the tubing string. In addition or alternately, the produced fluids may require flow rate control, as by use of chokes that are sometimes called inflow control devices (ICDs).

When natural inflow from the well is not economical, the well may require wellbore treatment termed stimulation. This is accomplished by pumping stimulation fluids such as fracturing fluids, acid, cleaning chemicals and/or proppant laden fluids to improve wellbore inflow.

In one previous method, the well is isolated in segments and one or more segments are individually treated so that concentrated and controlled fluid treatment can be provided along the wellbore by injecting the wellbore stimulation fluids from a tubing string through a port in the segment and into contact with the formation. After wellbore fluid treatment, the stimulation fluids are sometimes allowed to back flow from the formation into the wellbore tubing string. Thereafter, fluids are produced from the formation. In some embodiments, the produced fluids also enter the tubing string for flow to the surface. Where a wellbore frac tool also provides for inflow control, it is useful if fracing fluids not be forced out through the same ports that offer inflow control.

SUMMARY

In accordance with a broad aspect of the present invention, there is provided a selectively openable inflow control sub comprising: a tubular body including a wall defining an outer surface and an inner bore, an inflow port through the wall of the tubular body, an inflow controller to control inflow through the inflow port and a sliding sleeve valve slidable within the inner bore between a closed-port position, closing the inflow port, and an open-port position, opening the inflow port to fluid flow therethrough, the sliding sleeve valve being axially moveable from the closed-port position and the open-port position by pushing the sleeve with a mill string.

In accordance with another broad aspect of the present invention, there is provided a method for a wellbore operation, the method comprising: running a tubing string into a wellbore to a desired position for treating the wellbore; running a mill through the tubing string to apply an axially directed force to a sliding sleeve valve to move the sliding sleeve valve axially through the tubing string from one position to another position; and removing the mill from the tubing string.

It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable for other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

A further, detailed, description of the invention, briefly described above, will follow by reference to the following drawings of specific embodiments of the invention. These drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. In the drawings:

FIG. 1, specifically FIGS. 1 a and 1 b, are side elevation and sectional views through a wellbore inflow control sub.

FIG. 2 show a wellbore sub. Specifically FIGS. 2 a and 2 b, are side elevation and sectional views through a wellbore sub including both an inflow controller and a wellbore treatment mechanism. FIGS. 2 c to 2 h show a wellbore operation employing the sub.

FIGS. 3 a to 3 f are sectional views through a wellbore string installed in a wellbore and show a wellbore operation employing the wellbore string.

FIGS. 4 a to 4 d are enlarged portions of components of the sleeves of FIG. 3.

FIGS. 5 a to 5 c are sectional views through wellbores with tubing strings installed therein.

DESCRIPTION OF VARIOUS EMBODIMENTS

The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

This invention relates to solutions for selectively openable inflow control in a wellbore including a sub, a wellbore treatment string and a method for wellbore operations.

Various solutions for selectively openable inflow control of produced fluids are disclosed here. The inflow control can be by screening, choking, etc. Herein, the term inflow controller is employed to reference a mechanism for inflow control including screens (i.e. including mesh, sintered discs, filtering media, etc.) and chokes (i.e. ICDs, restricted orifices, labyrinth channels, gates, remotely controlled valves, etc.)

A method for a wellbore operations includes running a tubing string into a wellbore to a desired position for performing an operation in the wellbore; running a mill through the tubing string to apply an axially directed force to a sliding sleeve valve to move the sliding sleeve valve axially through the tubing string from one position to another position; and removing the mill from the tubing string. While the force is normally directed as the mill is run down into the tubing string, it is possible that the force could be applied when returning the milling back toward surface. In one embodiment, the sliding sleeve valve controls the open and closed condition of a fluid port and the force moves the sleeve to open or close the port.

A selectively openable inflow control sub includes a tubular body including a wall defining an outer surface and an inner bore, an inflow port through the wall of the tubular body, an inflow controller to control inflow through the inflow port and a sliding sleeve valve in the bore slidable within the bore between a closed-port position, closing the inflow port, and an open-port position, opening the inflow port to fluid flow therethrough. The sliding sleeve valve is axially moveable from the closed-port position and the open-port position by pushing the sleeve with a mill string. In particular, the sliding sleeve valve includes a mill protrusion that defines a diameter less than the milling diameter for the tubular body. The mill protrusion includes a singular, plural or annular protrusion that extends into the bore and constricts the inner diameter of the bore at that location to be less than the milling diameter. The milling diameter is about the same as the drift diameter through the bore.

The sleeve only becomes stopped against further axial movement through the bore when the sleeve reaches its open-port position. Thus, while the sleeve may be releasably secured in the closed-port position, the bore is free of any obstructions to the axial sliding movement of the sleeve until the sleeve is positioned in the open-port position.

While the selectively openable inflow control solutions are sometimes disclosed in combination with fracturing ports, it is to be understood that they can be used alone or in combination with other tubing string assemblies.

FIG. 1 disclose a selectively openable inflow control sub 10. FIG. 1 a shows a side elevation of the sub and FIG. 1 b shows a sectional view along long axis x of the sub.

Sub 10 includes a tubular body 12 including a wall defining an outer surface 12 a and an inner bore 12 b and ends 12 c, 12 d. The ends are formed for connection into a tubing string. In one embodiment, for example, ends 12 c, 12 d are threaded. Because the operation of the sub, one end 12 c is considered the upper end and the other end 12 d is considered the lower end. In operation, upper end 12 c is secured uphole from lower end 12 d. While the wall is illustrated as formed in parts, this is for ease of manufacture and, of course, modifications may be made thereto for example, to construct the wall as a single piece or in many pieces connected together.

Sub 10 further includes an inflow port 14 extending through the wall and, thereby, providing a fluid flow path between outer surface 12 a and inner bore 12 b. An inflow controller is positioned to control flow through inflow port 14. The inflow controller includes a screen 18 and a choking nozzle 20 in the inflow port. However, as noted above, other, fewer or additional inflow controllers may be employed, as desired. For example, while a choking nozzle 20 is installed in port 14, an operator may prefer in some applications to leave port 14 unchoked.

The construction of the inflow controller may be selected according to manufacturing preferences. For example, in this illustrated embodiment, the inflow port includes a wide annular recess on the outer surface, which is covered by screen 18 and a production sleeve 21. Production sleeve 21 closes off the annular recess and forms an annular space 14 a about the tubular wall that is a part of inflow port 14 and leads to inner bore 12 b.

Inflow port 14 is normally closed by a sleeve valve 22, but can be opened during milling through inner bore 12 b. Sleeve 22 includes a mill protrusion 24 against which the mill will be temporarily butted during its advancement. When the mill butts against the mill protrusion, a push force must be applied to mill out the mill protrusion. However, by installation of the sleeve 22 in a closed-port position such that it is free to slide down in inner bore, the push force of the mill applied against the mill protrusion can be enough to move the sleeve.

The sleeve is normally retained in its installed, run in position by a releasable lock that provides a holding force to resist inadvertent movement to the open-port position. Common releasable locks include shear pins 26, as shown, collets, snap rings, detents, etc. If a releasable lock is employed, the holding force of the releasable lock is selected also to be overcome by the push force of the mill applied against the mill protrusion. When the sleeve is stopped against further movement, as by abutment against a stop wall 28 in the string, the mill will mill out mill protrusion 24 before advancing further through the string.

Mill protrusion 24 is mounted or formed on sleeve and can be any protrusion that projects into inner bore 12 b and forms an inner diameter (ID) therepast that is smaller than the outer diameter (OD) of the mill. Generally the mill OD is substantially equal to the desired drift diameter (IDd) of the inner bore. Thus, mill protrusion 24 is a protrusion that projects to define an ID less than IDd.

The mill protrusion can, for example, be any singular, plural or annular protrusion on the sleeve's inner surface. Mill protrusion 24, for example as shown, can be in the form of a ball stop, which is often a frustoconical surface tapering from upper end to lower end. Although in this embodiment, it serves no purpose for stopping a ball, it is readily formed and therefore convenient. Also, its annular surface presents a substantially continuous surface without uneven, uphole projections such that the milling head tends not to catch thereon. The mill protrusion need not have any particular ID. For example, where a ball seat form is used, it can be run with any ball seat size.

Sleeve 22 is sized relative to the space between port 14 and wall 28 such that the sleeve can move from an overlapping position over port 14 before it is stopped against wall 28. Sleeve 22 is positioned in an annular recess, one end of which is wall 28 and the annular recess is free of any lower stops other than wall 28 so that the mill protrusion can only start to mill through the mill protrusion against which it is butted until the sleeve is stopped against wall 28 and therefore when sleeve is clear of port.

Sub 10 may further include seals 30 between sleeve 22 and the wall to seal against leakage through port 14 when the sleeve is in the closed-port position.

In this embodiment, the sleeve is retained from spinning in its installed and moved positions, as by use of a torque pin/slot 32 a, 32 b. This is useful as it allows the sleeve mill protrusion to be held against rotation so that it can be milled through when the sleeve hits wall 28.

Sleeve 22 may have a profile 34, such as an annular recess, for engagement by a shifting tool to provide for a contingency shifting operation. The profile is recessed out of the drift inner diameter IDd such that it remains even after milling through the sleeve.

Sleeve 22 may include another releasable lock that holds the sleeve in the port-open position, so it doesn't inadvertently slip back into the port-closed position. For example, in this embodiment, a snap ring 36 is carried on sleeve and a groove 38 is positioned in the annular recess to catch the snap ring. The snap ring is ramped such that it can be forced out of engagement with the groove if a shifting tool engages the sleeve and seeks to slide it. The groove and snap ring are positioned to engage when the sleeve is moved clear of the port.

Sleeve 22 over inflow port 14, therefore, is closed until a mill is run to mill out the ID of the tubing string. This milling may be solely to open the inflow-controlled port or to remove other string constrictions such as ball seats. Sometimes, for example, the selectively openable sub of FIG. 1 may be run with a wellbore treatment port. In such an embodiment, inflow port is closed during wellbore treatments such as fracturing such that high pressure flows do not pass through inflow port 14.

The tubular can be installed in a tubing string by connecting other tubulars on its top and bottom sub ends.

In FIG. 2, a selectively openable inflow control sub 110 is shown having an inflow controller in combination with a fluid treatment port, herein shown as a frac port 140. The frac port is openable when a fluid treatment is to be carried out through the frac port. For example, in the embodiment as shown, frac port 140 is closed with a frac sleeve 142 that has a ball seat 144 formed on its inner facing surface. The frac sleeve can be moved to open the frac port by dropping a suitably sized ball 146 that lands in seat 144, creates a seal thereacross forming a piston effect across which a pressure differential can be established to move the ball and sleeve. The force created is sufficient to overcome the holding force of a releasable lock, such as shear pins 148, holding sleeve 142 in place. A lock member, such as a snap ring 150, may be employed to lock the sleeve in its final position.

When the fluid treatment is complete through the frac ports 140, the production (inflow) ports 114 can be opened. As noted above with respect to FIG. 1, the production ports may be closed by a sleeve 122 that carries a mill protrusion 124 that protrudes into the inner bore and presents a diameter ID less than the drift diameter IDd of the bore. When it is desired to open sleeve 122, a mill can be run into the hole. The mill, generally being sized to open the inner bore to its full open IDd, will butt and apply a pushing force against mill protrusion 124 as it moves through the string. Milling through the string, therefore, automatically opens the production ports, while also removing any ball seats for opening of the inner bore to full open drift diameter IDd.

Sleeve 122 for the production ports 114 may be moveable to close the frac ports 140, while opening the production ports.

In this embodiment, inflow controller includes a screen 118. Screen 118 has a mesh size to occlude proppant used in the frac treatment.

Seat 144 has an inner diameter less than the diameter ID across the mill protrusion. Thus, by using ball 146 with an outer diameter less than ID but greater than the seat inner diameter, the ball can pass through sleeve 122 without operating it and then land on seat 144 and open sleeve 142.

The operation of the sub of FIGS. 1 and 2 may be better understood by reference to FIGS. 2 b to 2 h. The sub is run into a wellbore 104 in the condition shown in FIG. 2 b. When it is desired to open the ports 140 (FIG. 2 c), a ball 146 is launched to pass through the string 102 into which the sub is connected. The ball can pass through protrusion 124, but lands and seals on seat 144 of sleeve 142. The ball causes a piston effect to be generated on sleeve 142 and a pressure differential develops that overcome the holding force of shear pins 148. As shown in FIG. 2 d, this allows sleeve 142 to move clear of the fluid treatment ports 140 and fluid, arrows F, can exit inner bore 112 b and contact the formation.

After the fluid treatment operation is complete, the well may be flowed back, arrows BF, wherein fluids from the wellbore flow back into the string inner diameter 112 b. This removes ball 146 and cleans up the well of treatment fluids (i.e. gel, proppant, etc.). Back flow may be permitted through ports 140. This process may be additionally beneficial in this method, since such fluids can pass through ports 140 but may clog the screen 118 once production flow is opened.

When desired to initiate production flow, as shown in FIG. 2 f, the frac ports 140 are closed and production ports 114 are opened. To do so, a mill 160 is run through inner bore 112 b of string 102 to open up the seats. Mill 160 has an OD that opens the well substantially to IDd and therefore acts upon mill protrusion 124 of sleeve 122 and seat 144 of sleeve 142. In particular, as the mill contacts the profile presented at mill protrusion 124 in production sleeve 122, a push force is applied to protrusion 124. Since sleeve 122 is unobstructed other than by shear pins 126, once the force is sufficient to overcome shear pins 126, the sleeve moves down instead of being milled up. By installing sleeve 122 in a position where it can be moved down and selecting the shear pin holding force to be less than the force required to mill the protrusion, this ensures that the mill pushes the sleeve rather than mills into protrusion 124, even though protrusion 124 is formed of a millable material.

Sleeve 122 moves down until it is stopped against the upper end of sleeve 142. This movement of sleeve 122 opens production ports 114 and closes frac ports 140. In particular, sleeve 122 is moved to be clear of ports 114 and is repositioned to overlie frac ports 140. When sleeve 122 butts against upper end of sleeve 142, it is stopped against further axial movement. Continued force on mill 160, removes protrusion 124.

As shown in FIG. 2 g, the milling operation can proceed and, for example, seat 144 may be milled out as well. Thereafter, the mill may be removed. The string is left with a full open diameter generally equal to IDd.

Production, arrows P, from the reservoir 104 passes through the inflow controller, herein screen 118, and port 114. Because of screen 118, hydrocarbons free of oversize matter are produced into the inner bore 112 b and thereafter to surface. Proppant, if any, from the fluid treatment remains in place in the annulus. No flow is possible through frac ports 140, as sleeve 122 remains thereover. Sleeve 122 may carry seals 130 that are positioned to straddle ports 140 when in the overlying position.

FIG. 3 show another string 202 in position in a wellbore 204. The string includes a selectively openable and recloseable inflow control sub 210 connected adjacent a selectively openable and closeable fluid treatment sub 211. The string components are connected such that they share a common inner bore 202 b through which tools and fluids may be conveyed.

Although the two tools may be employed independently, a combination of the tools allows the formation accessed by the tool to the fluid treated (i.e. fraced) through a frac port 240 and flowed back if desired. Thereafter, an inflow controlled inflow port 214 may be opened while the frac port 240 is closed.

Specifically, the illustrated string includes selectively openable and reclosable inflow control sub 210 with a production sleeve 222 over inflow port 214. Inflow port 214 extends from outer surface 212 a of the sub to the inner bore 212 b and has mounted therein a sand screen 218 and a flow restrictor 220. Production sleeve is moveable to open and close port 214. In this embodiment, sleeve 222 has an opening 223 that can be moved into or out of alignment with port 214 to open or close it. Production sleeve 222 carries a mill protrusion 224 that extends into inner bore 202 b and presents a constriction having an inner diameter less than the normal full open diameter of inner bore 202 b.

Sleeve 222 is positioned in an annular groove in the inner wall of the sub and is positioned with a space between the lower end 222 a of the sleeve and end wall 228 of the groove. Sleeve 222 is held in this position by a releasable locking member, here a collapsible snap ring 226 a engaged in a groove 226 b.

Production sleeve 222 includes profiles 234 a, 234 b for accepting engagement with a shifting tool.

Selectively openable and closeable fluid treatment sub 211 includes a sleeve closure 242 over its frac port 240. Sleeve closure 242 is axially moveable through inner bore 202 b from a port-closed position to a port-open position. Sleeve closure 242 includes a ball seat 244 and a ball may be landed thereon to provide the axial force required to move the sleeve. Sub 211 includes a closing sleeve 252 that is axially moveable through inner bore 202 b from a retracted position to a port-closing position. Closing sleeve 252 includes a mill protrusion 254 thereon that extends into inner bore 202 b and presents a constriction having an inner diameter less than the normal full open diameter of bore 202 b. Closing sleeve 252 is normally held in the retracted position by releasable locking structure, herein shear pins 256. Closing sleeve 252 includes profiles 258 a, 258 b for accepting engagement with a shifting tool.

The inner diameters through mill protrusions 224 and 254 are greater than the inner diameter across ball seat 244.

This combination of tools gives the operator the ability to drop a ball 246 (FIG. 3 b), which passes, arrow B, through the first two ID restrictions formed by mill protrusions 224, 254. It can be seen at phantom ball 246, that the ball passes through protrusions 224, 254 without affecting them. The ball then lands on the frac port closure sleeve seat 244 therebelow. After the ball seats in the seat, FIG. 3 c, a pressure differential is established across the ball/seat that opens the fracturing port allowing stimulation fluids, arrows F, to flow through frac port 240 formerly protected by that sleeve. This treats the section of the reservoir accessed through port 240.

As shown in FIG. 3 d, after the stimulation, the ball may or may not be flowed back, arrows BF, to surface. Some operators want to flow back a little to clean up some of the chemicals used in the fracturing operation and others do not care to do so. Back flow may proceed through ports 240, as they are already open and present a substantially unrestricted inlet to string 202.

After the stage has been fluid treated and any back flow is permitted, FIG. 3 e, a mill 260 is run in, which opens inflow port 214 and closes the fracturing port 240, while milling out the mill protrusions 224, 254 and the seat 244. In particular, the mill, when being advanced through string 202, bears against anything in its path. Thus, anything that protrudes into the inner diameter 202 b and presents a constriction narrower than the outer diameter of the mill, is contacted by the mill. As shown, mill 260 can be pushed down from surface and lands against the mill protrusion on sleeve 222 and the mill protrusion on sleeve 252 and applies a pushing force to overcome their releasable holding mechanisms 226 a, 256, respectively and to move each sleeve until the sleeves each become stopped. When each sleeve is stopped against any further movement, the mill mills through the mill protrusion on that sleeve. Both the production sleeve 222 and the frac port closing sleeve 252 are moved in the same way. FIG. 3 e shows a stage in the milling operation wherein sleeve 222 has been moved to open port 214, the mill protrusion of sleeve 222 has been milled out and mill 260 has butted against protrusion 254 and pushed closing sleeve 252 to the port-closed position. Continued movement of the mill downhole, arrow M, will mill off mill protrusion 254 and ball seat 244.

With the frac port closed and the inflow control inflow port open (FIG. 3 f), the well is now ready to produce through the inflow controlled (in this case screened and choked) section of the tool.

If the operator ever wants to re-close the inflow controlled section, it is possible by running the appropriate shifting tool to engage profile 234 a. Likewise, if the operator ever wants to re-open frac port 240, re-closing sleeve 252 can be moved away from the port also by running the appropriate shifting tool to engage 258 a and a re-frac operation can be conducted therethrough.

There can be no actuation by dropping balls or milling since the ball seat and mill protrusions are milled away. All production and fracturing port opening and closing is now done with the shifting tools.

As shown in FIG. 4, each of the production sleeve 222 and the frac port closing sleeve 252 can have different forms of shifting tool profiles 234 a/b, 258 a/b, respectively, so there is no mistaking which part is being shifted. The profiles can be formed differently by selecting the axial length L1 of the profile indentation and/or the length L2 of the sleeve surfaces about the profile. Note that the lengths L1 of the indentations 234 a, 258 a differ, with indentation 234 a having a shorter axial length than indentation 258 a and the shift tools intended to be used to shift the sleeves can be formed with consideration as to the lengths L1 and L2. Thus, as shown in FIG. 4 a, profile 234 a on sleeve 222 can be engaged by shift tool 266 but cannot accept engagement with a larger shift tool key 268, FIG. 4 b. Likewise, as shown in FIG. 4 c compared to FIG. 4 d, sleeve 252 has a longer length profile 258 a intended to be engaged by larger shift tool key 268, but will not accept engagement with key 266. Thus, depending on which sleeve is to be moved and in which direction (uphole or downhole), a shifting tool with the appropriate key can be employed. A shifting tool can be run right through the string, knowing it can only engage the profiles with which it is formed (i.e. sized or shaped) to fit.

The use of two different forms of profiles allow the individual opening and closing of production sleeve 222 without moving closing sleeve 252 and vice versa. This gives the operator the option to re-treat the well or to close the production sleeve if there is water break through.

The string of FIGS. 3 and 4 gives the operator many options for treatment and control.

In FIG. 5, various tubing strings are shown with combinations of the selectively openable subs. In these Figures, a string 302 has a plurality of packers 370 that can be set in the wellbore 304 to form a plurality of isolated stages I, II, etc. The strings are each installed in an open hole (uncased), horizontal section of the well. However, the strings may be employed in wells that are cased and/or non-horizontal, as desired.

In the embodiment, of FIG. 5 a, each stage includes a sub 310 a including a fluid treatment section including fluid treatment ports 340 a and an inflow controlled section, including a screened interval 318 a. This sub, for example, may be similar to that described above in respect of FIG. 2 b or 3 a.

In the embodiment of FIG. 5 b, each stage includes a sub 310 b′ including a fluid treatment section including fluid treatment ports 340 b and an inflow controlled section, including a screened interval 318 b′. Each stage also includes another sub 310 b″ intended only for controlled inflow, having a screened interval 318 b″ but without fluid treatment ports. Sub 310 b″ may be similar to that described above in respect of FIG. 1 b and sub 310 b′ may be similar to that described above in respect of FIG. 2 b or 3 a. This string configuration allows both fluid treatment and controlled inflow in each section. However, the opportunity for inflow is greater than that in FIG. 5 a. The number of subs intended only for inflow can be selected as desired. While two per stage are shown here, other numbers are possible.

In the embodiment of FIG. 5 c, each stage includes one or more subs 310 c for inflow control. This string configuration allows controlled inflow in each section, but is not well suited for wellbore treatment with high pressure outward flows. Such a string may be employed for example, in a well that has been previously treated or requires no treatment, but where it is desired to control the open/closed condition of the inflow ports and in stages.

Although not shown, a plurality of combination subs (similar to those of FIG. 2 b or 3 a) may be used in a single stage, if deformable balls or seats, openable kobes or shiftable subsleeves are employed.

Referring again to FIG. 5, the strings may be employed in wellbore operations. For example, the string 302 of FIG. 5 b, may be run in and set in place in the well. This may include setting plurality of packers 370. Although the string includes ports 340 b and fluid inflow ports beneath screens 318 b′, 318 b″, the tubing string can hold pressure when these ports are closed by internal sleeves and, in one embodiment, packers may be set by pressuring up the string.

When packers 370 are set, stages may be defined in the well. Each stage is between a pair of adjacent packers, which therebetween create an isolated interval. To fluid treat the formation in stages, balls are dropped to sequentially open the frac ports 340 b. Because there are ball seats in all stages of this embodiment, the ball for opening the frac ports in the most distal stage, stage I, is the smallest and each ball for each stage closer to surface is progressively larger. Thus, for each stage, a ball is dropped to open the fracturing port and pumping fluid through the opened ports 340 b then stimulates the stage. This is repeated until all stages are fraced. Thereafter, the balls may be produced back or left in the string. All of this occurs with the ports closed beneath screens 318 b′, 318 b″, thus screens do not become contaminated by fluid treatment gels, proppant, etc.

By running through the string with a mill, the sleeves covering the production ports (under the screens 318 b′, 318 b″) are opened by pushing on their mill protrusions. Movement of the mill also closes ports 340 b. In particular, either: production sleeve movement by mill opens the production ports and closes the frac ports or mill moves a closing sleeve. With the production ports open, the mill can be removed and produced fluids can be screened, and perhaps pressure regulated, as they enter the tubing string in their flow towards surface.

In the illustrated embodiment, a screen is used to control inflow through the production port, but other inflow control mechanisms may be employed. For example, alternately or in addition, inflow control may be provided by a labyrinth channel system, a choke, a nozzle, an erodible disc, etc. In another embodiment, the inflow control mechanism is adjustable and in one embodiment remotely adjustable, such as while positioned downhole.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 USC 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or “step for”. 

1. A selectively openable inflow control sub comprising: a tubular body including a wall defining an outer surface and an inner bore, an inflow port through the wall of the tubular body, an inflow controller to control inflow through the inflow port and a sliding sleeve valve slidable within the inner bore between a closed-port position, closing the inflow port, and an open-port position, opening the inflow port to fluid flow therethrough, the sliding sleeve valve being axially moveable from the closed-port position and the open-port position by pushing the sleeve with a mill string.
 2. The selectively openable inflow control sub of claim 1 wherein the sliding sleeve valve includes a mill protrusion that defines a diameter less than an outer diameter of the mill string.
 3. The selectively openable inflow control sub of claim 2 wherein the diameter at the mill protrusion is less than a drift diameter.
 4. The selectively openable inflow control sub of claim 2 wherein the mill protrusion is an annular protrusion.
 5. The selectively openable inflow control sub of claim 2 wherein the mill protrusion has a frustoconical upper surface.
 6. The selectively openable inflow control sub of claim 1 wherein the sliding sleeve valve is held in the closed-port position by a releasable lock selected to be overcome by the force applied by a mill string.
 7. The selectively openable inflow control sub of claim 1 further comprising a stop wall in the inner bore and positioned downhole of the sliding sleeve valve, the stop wall positioned to stop axial movement of the sliding sleeve valve when it reaches the open-port position.
 8. The selectively openable inflow control sub of claim 7 wherein the stop wall is a portion of the wall.
 9. The selectively openable inflow control sub of claim 7 wherein the stop wall is an end of a sleeve valve positioned downhole of the sliding sleeve valve.
 10. The selectively openable inflow control sub of claim 7 wherein the inner bore is free of obstructions to the axial sliding movement of the sleeve between the closed-port position and the stop wall.
 11. The selectively openable inflow control sub of claim 1 further comprising a shifting profile on the sliding sleeve valve.
 12. The selectively openable inflow control sub of claim 1 further comprising a frac port through the wall, the frac port axially spaced from the inflow port.
 13. The selectively openable inflow control sub of claim 12 further comprising a sleeve valve in the inner bore and being moveable from a closed position overlying the frac port to an open position, retracted at least in part from the frac port.
 14. The selectively openable inflow control sub of claim 13 further comprising a ball seat on the sleeve valve for catching a ball launched to move the sleeve valve hydraulically.
 15. The selectively openable inflow control sub of claim 12 wherein the sliding sleeve valve overlies the frac port in the open-port position.
 16. The selectively openable inflow control sub of claim 12 further comprising a closing sleeve moveable to overlie the frac port, when the sleeve valve is in the open position.
 17. The selectively openable inflow control sub of claim 16 further comprising a first shifting profile on the sliding sleeve valve and a second shifting profile on the closing sleeve, and the first shifting profile has a form different from the second shifting profile such that a tool that engages the first shifting profile cannot engage the second shifting profile.
 18. A method for a wellbore operation, the method comprising: running a tubing string into a wellbore to a desired position for treating the wellbore; running a mill through the tubing string to apply an axially directed force to a sliding sleeve valve to move the sliding sleeve valve axially through the tubing string from one position to another position; and removing the mill from the tubing string.
 19. The method of claim 18 wherein the axially directed force is applied as the mill is run down into the tubing string.
 20. The method of claim 18 wherein the sliding sleeve valve controls the open and closed condition of a fluid port and the force moves the sleeve to open or close the fluid port.
 21. The method of claim 18 wherein the axially directed force moves the sliding sleeve valve to open a port controlled by the sliding sleeve valve and permitting fluid to pass from the wellbore into the tubing string through the port.
 22. The method of claim 21 further comprising controlling inflow through the port.
 23. The method of claim 18 wherein the axially directed force is applied to a protrusion on the sliding sleeve valve that protrudes into the path of the mill.
 24. The method of claim 23 further comprising milling through the protrusion.
 25. The method of claim 23 further comprising pushing the sliding sleeve valve against a stop and milling through the protrusion.
 26. The method of claim 18 further comprising opening a frac port in the tubing string by applying a force to a first sliding sleeve valve for the frac port; and injecting stimulating fluids through the frac port. 